This invention relates to a contactless relay which relies upon electronic circuitry to perform the same function as a relay with contacts.
A relay having mechanical contacts, such as a reed relay, is employed widely in the art for transmitting signals between two systems having different signal levels, as when interfacing a numerical control device and machine tool. The relay with contacts applied in this fashion is ideal in that its output terminals are non-polarized, its input and output are isolated DC-wise, and it is small in size. Nevertheless, relays with contacts of a mechanical nature are disadvantageous in that they have a shorter lifetime than contactless relays owing to contact wear, and in that they also exhibit lower operating speed. In response to the need for further development of a relay without contacts, many contactless relays incorporating different kinds of electronic circuitry have been proposed, but none have the aforementioned excellent properties possessed by relays provided with contacts.